In recent years, in the field of NC machine tools, progress has been made in multiple function machining enabling complicated and diverse shapes of products to be automatically machined by providing turning tools, drills, mills, and other various types of tools exchangeably on tool rests and enabling execution of turning, drilling, milling, and other various machining processes using them.
Further, in NC lathes and other automatic lathes (that is, lathes able to automatically perform machining), multi-function type NC lathes designed to shorten the machining time by centrally placing at least one spindle and at least one tool rest, both operable under the control of a plurality of lines, on a single lathe bed to enable simultaneous different types of machining (for example, outer diametrical cutting and boring) on the same workpiece (for example, bar) or simultaneous machining of different workpieces.
Note that the term “line” means a combination of a group of control axes controlled by a single machining program (including case of only one control axis). When it is possible to set a plurality of types of combinations of groups of control axes on a single NC machine tool, the control system in that NC machine tool is generally called “multi-line control (or multi-path control)”.
When trying to perform various types of machining processes simultaneously or in a desired order on a single workpiece in such a multiple function machining NC machine tool, the work of producing the series of machining programs and registering them in the NC device requires advanced programming skills, so tends to place a considerable burden on the operator.
On the other hand, in the field of NC machine tools, various configurations of automatic programming apparatuses provided in relation to NC devices have been proposed to reduce the labor demanded from the operator at the time of preparing the machining programs. This type of automatic programming apparatus usually is provided with a CPU, memory, keyboard, display, etc. and is designed to acquire the data required for executing machining processes from dialog type instructions and input data from the operator for various selection items or required items displayed in order on the display and, if necessary, geometric data of the machined product input by a drawing format through a graphic input device such as a CAD system and to use this to automatically produce the required machining programs. According to this automatic programming apparatus, the work of the operator inputting the machining programs by phrases is eliminated, so even an operator with inferior programming skills can prepare complicated machining programs in a relatively short time.
In the above conventional automatic programming apparatus, while the time of production of machining programs by the operator is effectively shortened, the various data required for the programming is judged and set by the operator with reference to the design drawings of the machined product, so sufficient knowledge about the machining processes or tool attributes is required from the operator.
For example, when producing a series of machining programs for executing the various automatic cutting processes for a single machined product using a multi-spindle, multi-line control type NC lathe provided with a plurality of types of tools on a plurality of tool rests, the operator has to read the types of processes required for the machining from the design drawings of the machined product and, while considering the material of the workpiece, suitably judge, set, and input the data required for each machining range in the individual processes (such as types of tools, movement positions of noses, relative cutting speeds of noses and/or relative feed rate of tool rests). In particular, data relating to the cutting conditions such as the cutting speed and the feed rate vary in most suitable values in accordance with the tool nose and the material of the workpiece. The accuracy of judgement and the resultant machining accuracy tend to be governed by the level knowledge or experience of the operator.
Further, when producing a multi-line control program for executing various automatic cutting processes on a single machined product by such a multi-spindle, multi-line control type NC lathe in parallel by a plurality of lines, the operator is required to read the types of processes required for the machining from the design drawings and then suitably judge and design what line and at what time to execute the individual processes would be most advantageous in terms of work efficiency. In particular, when attaching designated tools to be used in the cutting processes on the tool mounts of the tool rests, it is sometimes necessary to use special tool holders depending on the types of the designated tools or the configurations of the tool rests. In that case, however, the operator must decide how to allocate and attach the plurality of designated tools to the plurality of tool mounts provided on a single tool rest with reference to the numbers of the plurality of types of tool holders in stock for the different types and their attributes (such as types of mountable tool rests, types of processes used for and/or attributes of tools for use).
In this way, to produce a highly efficient multi-line control program by the conventional automatic programming apparatus, the operator was required to be fully knowledgeable about the machine configuration of the NC machine tool covered and maintain an accurate grasp of the attributes of the plurality of types of tool holders able to be used in that NC machine tool and the numbers in stock and then suitably allocate and designate attachment locations of the plurality of designated tools to the plurality of tool mounts of one or more tool rests. As a result, a tremendous amount of time and effort is spent on producing the multi-line control program. Further, the quality of the automatically produced multi-line control program (such as length of cycle time, appropriateness of tool management and/or machining accuracy) tends to be remarkably affected by the level of knowledge or experience of the operator.
Further, in the conventional automatic programming apparatus, when the operator checks the content of the produced machining programs, the troublesome work is required of displaying and reading the series of blocks describing the machining programs on a display. With check work of such a program display method, it was hard to obtain a grasp of the time spent for the individual processes and difficult to optimize the programming for shortening the machining time. Further, judging whether the order of execution of the plurality of processes for producing a single machined product can be changed for streamlining the machining work or predicting the impact of a change in the order of processing on the series of machining programs as a whole was extremely difficult with the conventional program display method.